The present invention relates to a tire position determination system that determines a mounting position of a tire when monitoring air pressure of the tire.
Tire pressure monitoring systems are installed in vehicles to improve safety. One type of a tire pressure monitoring system directly monitors the air pressure of each tire using a tire pressure detector coupled to each tire that transmits a tire pressure signal. The tire pressure signal includes data of the pressure detected by a sensor in the tire pressure detector. The tire pressure signal also includes a tire ID stored in the corresponding tire pressure detector. This allows for the pressure to be recognized and the tire to be located. When the pressure of a tire is low, the driver is informed of the location of the lower pressure tire.
The tire pressure monitoring system includes an automatic locating function that periodically checks the position of each tire so that the tire positions are accurately stored even when the tire positions are changed or a tire is exchanged. To implement the automatic locating function, an initiator (trigger device) may be arranged in the wheel well for each tire. The initiator transmits a signal to a corresponding tire pressure detector to locate the tire (refer to, for example, Japanese Laid-Open Patent Publication Nos. 2006-062516 and 2012-126341).
The mounting position of a tire is changed when, for example, the ignition switch is off, that is, when the engine is stopped. Thus, when the ignition switch goes on after changing the mounting position of a tire, there is a need to readily determine whether or not the mounting position of the tire has been changed. This may be achieved by, for example, arranging an initiator in each tire well and determining whether or not the mounting position has been changed by checking the response from each initiator. In this case, however, the initiator arranged in each wheel well increases the number of components.